DP-900 Describe core data concepts Practice Test 8 — 15 Questions

Question 1

A retail company stores product inventory data in a fixed-schema table with columns for ProductID, ProductName, QuantityInStock, and ReorderLevel. How should this data be classified?

Accepted Answer

Structured data. This data is classified as structured data because it conforms to a fixed schema with clearly defined columns (ProductID, ProductName, QuantityInStock, ReorderLevel) and data types, stored in a relational table. Structured data is highly organized, easily queryable via SQL, and follows a rigid schema, which matches the description of the inventory table.

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Semi-structured data

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Unstructured data

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Streaming data

Question 2

A bank processes a fund transfer transaction. The system debits $100 from Account A and then credits $100 to Account B. If the system crashes after debiting Account A but before crediting Account B, the database automatically reverts the debit. Which ACID property ensures this behavior?

Accepted Answer

Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work. If any part of the transaction fails (e.g., a crash after debiting Account A but before crediting Account B), the entire transaction is rolled back, reverting any partial changes like the debit. This all-or-nothing behavior is the core of atomicity in database systems.

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Consistency

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Isolation

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Durability

Question 3

A social media platform stores user posts as JSON documents. Each document contains text content, image URLs, timestamps, and user tags. The structure is consistent for most fields, but users can add custom key-value pairs. How should this data be classified?

Accepted Answer

Semi-structured data. The data is semi-structured because it has a consistent schema for most fields (text, image URLs, timestamps, user tags) but allows custom key-value pairs, which introduces schema flexibility. JSON documents inherently support this mix of fixed and variable attributes, fitting the semi-structured data classification. This aligns with Azure Cosmos DB's handling of JSON items, where each document can have a different set of properties.

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Structured data

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Unstructured data

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Relational data

Question 4

A company collects customer feedback forms. Each form contains always-present fields like CustomerID and SubmissionDate, but also a free-text Comments field and optional fields like Rating or ProductCategory that vary between forms. How should this data be classified?

Accepted Answer

Semi-structured data. The customer feedback forms contain a mix of structured fields (CustomerID, SubmissionDate) that follow a fixed schema and unstructured fields (free-text Comments) plus optional fields (Rating, ProductCategory) that may or may not be present. This combination of schema-optional and schema-fixed data within the same record is the hallmark of semi-structured data, which does not require a rigid schema like a relational table but still has some organizational properties (e.g., tags or key-value pairs). In Azure, this data is well-suited for storage in Azure Cosmos DB (using JSON documents) or Azure Blob Storage with metadata, rather than a strictly relational database.

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Structured data

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Unstructured data

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Relational data

Question 5

A banking application processes a funds transfer transaction consisting of two steps: debit $100 from Account A and credit $100 to Account B. If the system crashes after debiting Account A but before crediting Account B, the database automatically reverts the debit, restoring Account A to its original balance. Which ACID property guarantees this behavior?

Accepted Answer

Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work. In this scenario, the debit and credit are part of one transaction; if the system crashes after the debit but before the credit, the database management system (DBMS) automatically rolls back the entire transaction, undoing the debit to restore Account A's original balance. This all-or-nothing behavior is the defining characteristic of atomicity.

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Consistency

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Isolation

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Durability

Question 6

A company stores customer data in a SQL Server table with fixed columns (CustomerID, Name, Email, SignupDate). The company also stores application logs as JSON documents and marketing images as JPEG files. Which data type describes the customer data?

Accepted Answer

Structured data. Customer data stored in a SQL Server table with fixed columns (CustomerID, Name, Email, SignupDate) follows a rigid schema where each row has the same set of columns with defined data types. This conforms to the relational model, making it structured data. Structured data is organized into rows and columns with a fixed schema, enabling efficient querying via SQL.

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Semi-structured data

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Unstructured data

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Relational data

Question 7

A company stores customer data in a SQL table with fixed columns (CustomerID, Name, Email, SignupDate). They also store product images as JPEG files and application logs as JSON documents. Which of the following correctly classifies each data type?

Accepted Answer

SQL table: structured, JPEG: unstructured, JSON: semi-structured. A SQL table with fixed columns enforces a rigid schema, making it structured data. JPEG files are binary blobs with no internal schema, classifying them as unstructured. JSON documents use key-value pairs with flexible schemas, which is the definition of semi-structured data.

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SQL table: structured, JPEG: semi-structured, JSON: unstructured

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SQL table: semi-structured, JPEG: unstructured, JSON: structured

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SQL table: unstructured, JPEG: structured, JSON: semi-structured

Question 8

A retail company uses a point-of-sale (POS) system that records each sales transaction in a database. Each transaction involves reading the current inventory, updating the stock level, and recording the sale. The database must ensure that concurrent transactions do not interfere with each other, so that one transaction does not see partially updated data from another. Which property of a database transaction ensures this isolation?

Accepted Answer

Isolation. Isolation ensures that concurrent transactions do not interfere with each other, so each transaction sees a consistent snapshot of the database as if it were the only transaction running. In the POS scenario, isolation prevents one transaction from reading partially updated inventory data from another transaction, which could lead to overselling or stock discrepancies. This property is typically implemented through locking mechanisms or multi-version concurrency control (MVCC).

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Atomicity

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Consistency

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Durability

Question 9

A company updates a customer's address in a database. The update must ensure that all existing orders still reference a valid customer ID. The database checks the foreign key constraint and rejects the update if it would violate referential integrity. Which ACID property does this enforcement represent?

Accepted Answer

Consistency. Consistency ensures that any database transaction brings the database from one valid state to another, preserving all defined rules, including constraints like foreign keys. In this scenario, the foreign key constraint enforcement prevents an update that would leave orphaned order records, directly upholding the consistency property by rejecting the transaction if it violates referential integrity.

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Atomicity

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Isolation

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Durability

Question 10

A company receives data from a point-of-sale system. Each row contains TransactionID, ProductID, Quantity, and Price. The data has a fixed schema and is stored in a table. How should this data be classified?

Accepted Answer

Structured data. The data has a fixed schema with clearly defined columns (TransactionID, ProductID, Quantity, Price) and each row follows the same structure, which is the definition of structured data. In Azure, this would map directly to a table in Azure SQL Database or a fixed-schema table in Azure Synapse Analytics. The rigid schema and consistent data types make it ideal for relational storage and querying.

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Semi-structured data

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Unstructured data

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Transactional data

Question 11

A retail company stores customer transaction data in a relational database. Each transaction is recorded with a fixed schema including TransactionID, CustomerID, ProductID, Quantity, and TotalAmount. Which type of data does this represent?

Accepted Answer

Structured data. The data conforms to a fixed schema with defined columns (TransactionID, CustomerID, ProductID, Quantity, TotalAmount) and data types, which is the defining characteristic of structured data. In a relational database, this schema enforces consistency and allows for efficient querying using SQL, making it a classic example of structured data.

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Unstructured data

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Semi-structured data

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Binary data

Question 12

A global e-commerce platform uses a combination of relational and NoSQL databases. The order management system requires ACID transactions across multiple tables (Orders, OrderItems, Inventory). The product catalog uses a flexible schema to accommodate varying product attributes and is read-heavy. The session store requires low-latency key-value lookups with eventual consistency. Which of the following pairings of data stores best matches these requirements?

Accepted Answer

Order management: Azure SQL Database - Product catalog: Azure Cosmos DB (NoSQL API) - Session store: Azure Cache for Redis. Azure SQL Database provides full ACID transaction support across multiple tables, making it ideal for order management. Azure Cosmos DB (NoSQL API) offers a flexible schema and high read throughput for the product catalog. Azure Cache for Redis delivers sub-millisecond key-value lookups with eventual consistency, perfect for session storage.

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Order management: Azure Cosmos DB (NoSQL API) - Product catalog: Azure SQL Database - Session store: Azure Table Storage

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Order management: Azure Table Storage - Product catalog: Azure SQL Database - Session store: Azure Cosmos DB (NoSQL API)

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Order management: Azure Cosmos DB (Table API) - Product catalog: Azure Cache for Redis - Session store: Azure SQL Database

Question 13

A company stores customer information in a SQL database table with columns: CustomerID, FirstName, LastName, Email, SignupDate. They also store product images as JPEG files in Azure Blob Storage. Which statement correctly describes the types of data involved?

Accepted Answer

Customer data is structured, product images are unstructured.. Customer data stored in a SQL database table with defined columns (CustomerID, FirstName, LastName, Email, SignupDate) is structured because it adheres to a fixed schema with rows and columns. Product images stored as JPEG files in Azure Blob Storage are unstructured because they lack a predefined data model and are stored as binary large objects (BLOBs) without a schema. Option B correctly identifies this distinction.

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Customer data is unstructured, product images are semi-structured.

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Both are structured.

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Customer data is semi-structured, product images are unstructured.

Question 14

A financial database system ensures that once a transaction is committed, the data changes are permanently stored and will survive any subsequent system failure, such as a power outage or crash. Which property of ACID transactions does this describe?

Accepted Answer

D: Durability. D is correct because durability guarantees that once a transaction is committed, the changes persist permanently, even in the event of a system failure like a power outage or crash. In SQL Server, this is implemented via the write-ahead log (WAL) and checkpoint processes, ensuring committed data is flushed to disk before acknowledging success.

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A: Atomicity

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B: Consistency

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C: Isolation

Question 15

A financial company needs to store transactional records where each record has a fixed set of attributes (TransactionID, Amount, Date, AccountID). The data must support complex queries and enforce referential integrity. Which type of data store is most appropriate?

Accepted Answer

Relational database. A relational database (option C) is the most appropriate choice because transactional records with a fixed schema and the need for referential integrity (e.g., ensuring AccountID references a valid account) are best handled by a structured, ACID-compliant system like Azure SQL Database or SQL Server. Relational databases enforce constraints such as foreign keys and support complex queries using JOINs and aggregations, which are essential for financial reporting and auditing.

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Key-value store

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Document database

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Graph database